Alistair Darling was recently asked what he would do with Britain's bankers if they did not agree to lend more. "Put them in a room with [Shriti Vadera] and lock the doors for a couple of hours," he replied.

These attributes are reflected in the two nicknames most commonly used about her. To her enemies she is "Shriti the Shriek". But to others she is "Gordon Brown's representative on earth".

She spent eight years at the Treasury where she became a close adviser to Brown, who is said to have been her greatest champion. Other colleagues were less enthusiastic about a woman known to reduce junior members of staff to tears.

Her forceful approach was demonstrated during the demise of Railtrack in 2001. She was attributed with branding the company's shareholders "grannies who would lose their blouses" (although allies said this comment actually came from a different official).

When Stephen Byers was asked about her during the court case brought by Railtrack shareholders, he said: "She can be forceful and sometimes she can be a real sweetie."

Lady Vadera, who was created a life peer in July 2007, has described her relationship with the civil service as "challenging".

After less than a year at the Department for International Development, in 2008 she became minister for small business and competitiveness.

Her frosty relationship with the civil service has reportedly seen a high turnover of officials in her private office.

After a number of them quit when she joined the Department for Business, Alan Duncan, the shadow business secretary, questioned her behaviour. But a number of people leapt to her defence, with Stephen Alambritis of the Federation of Small Businesses saying: "If the civil service is complaining about her, then probably more ministers should be like her; she gets things done."

Born in Uganda, Vadera's family moved to India and then England, where she studied politics, philosophy and economics at Somerville College, Oxford.

She spent 14 years at UBS Warburg, the investment bank, and her work included advising governments of developing countries on a range of issues such as debt restructuring.

She was a trustee of Oxfam between 2000 and 2005 and is said to have worked closely with Brown on aid and debt relief policy.

In June 2007, Martin Vander Weyer, a former speechwriter for Vadera, wrote in the Spectator: "The serious-minded but likeable 30-something I knew has transmuted into the assassin of Railtrack, the ass-kicker of Transport for London, the axe-wielder from the Treasury whom departmental ministers fear as acutely as they fear Gordon himself, with whose total authority she speaks."